Spatial Orientations helps the human body determine the natural ability to maintain orientation (body position) in relation with the surrounding. On the ground, humans are able to maintain spatial orientation because of our exposure to the environment since young and we have built a sense of familiarity with our surroundings. However, when in the air, spatial orientation is not unfamiliar and creates “sensory conflicts” which prevent us from maintaining spatial orientation. “Statistics show that between 5 to 10 % of all general aviation accidents can be attributed to spatial disorientation, 90% of which are fatal” (FAA, n.d)
Why does it occur?
Human beings have sensory systems that help us to determine our equilibrium and tell us if we are sitting down from lying down to whether we are upside down. The three sensors are;
- Visually – We use our eyes, which will basically tell us what position we are in
- Vestibular System – is basically the organs in our inner ear that sense position by the way we are balanced. The vestibular system comprises of two components
- Semi circular canal, which indicated rotational movements ii.
- Otoliths – which indicate liner accelerations. The system as a whole will send signals to the neutral structures that control our eye movement, and to the muscles that keep us upright.
Figure 1: Vestibular System, which helps us to determine position by the way it’s balanced
Figure 2: Semi Circular canal (Endolymph, Cupula) movements that assists in determining direction
- Somatosensory system – Nerves in the skin, muscles, joints, hearing, feeling which assist in determining our equilibrium.
When does Spatial Disorientation Occur?
Spatial Disorientation occurs when the pilot does not have a visual reference. The pilots have no visual cues to determine his judgment, and there are a lack or false inputs from the vestibular system and the somatosensory system. Wrong information from any of the three systems, and an interaction of this sense may lead to incorrect information sent to the brain through nerves which may lead to pilot disorientation.
Types of Spatial Disorientation
- The Leans
I was practicing my first simulated Instrument flight with an instructor. I was told to maintain straight and level and follow a aircraft heading given to me. Initially, I found myself always constantly applying ailerons even thought it was a calm day. My instructor pointed out to me that this was because when I thought I was in straight and level, I was in actual fact banking to the right.
The lean is a spatial orientation, which is characterized by a false sense of bank when the aircraft is actually in level flight. This happened to me, and I had failed to confirm my Angle of bank with the instruments. “ If a bank is entered slowly, or is maintained long enough for fluid in the semicircular canal to stabilize” (Earl 2009), the aircraft might perceive that state of bank as straight and level.
- Coriolis Illusion
Coriolis Illusion is caused from the abrupt movements of the head, which can set the fluid in the semicircular canals moving in such a way as to create an overwhelming sensation of tumbling head over heels. The sensation can be so strong as to lead pilots to lose control of the aircraft. An example when this might be occurs for a pilot is the constant moving of head when looking at the charts in the cockpit and that looking up.
Vertigo also makes up spatial disorientation. Pressure vertigo when occurs when Eustachian tube is blocked and this prevents pressure in the middle ear from equalizing which leads to dizziness. Another form of vertigo is called flicker vertigo. Flicker vertigo is caused by an imbalance in the brains when exposed to low frequency flashing or very bright lights. This occurrence is very relevant for a pilot because of airports, which are lighted up and are very bright for identification purposes. For pilots in new Zealand, who are involved in General Aviation, this can occur when sunshine’s through propeller blades and there is a constant flickering. Vertigo Flicker can cause convulsions, paralysis and unconsciousness.
- Graveyard Spiral
Graveyard spiral occurs when there is a return to level flight following an intentional or unintentional prolonged bank turn.
“For example, a pilot who enters a banking turn to the left will initially have a sensation of a turn in the same direction. If the left turn continues (for more than 20sec) , the pilot will experience the sensation that the aircraft is no longer turning to the lift. At this point, if the pilot attempts to level wings, this action will produce a sensation that the airplane is turning and banking in the opposite direction. Pulling he control yoke/stick and applying power while turning would not be a good idea it would only make the left turn tighter, and if the pilot fails to roll wings level, the aircraft will keep turning till it hits the ground."
How can we prevent Spatial Disorientation?
- Take the opportunity to experience a Spatial Disorientation with an instructor
- Before flying with less than 3 miles visibility, obtain training and maintain proficiency in airplane control with reference to instruments
- When flying at night or in reduced visibility, use instruments
- Do not fly visually in deteriorating weather
- If you experience vestibular illusion, trust ur instruments
Human Performance. (2009). Massey University (190.107) .
Spatial Disorientation. (2004). American Institute of Aeronautics & Astronautics.
Aeromedical Spatial orientation and disorientation during flight: Illusions during the approach and landing. Retrieved from the World Wide Web: http://aeromedical.org/Articles/graphics/a&l3.jpg 24 August 2009
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